Notch inhibitors for use in the treatment of t-cell acute lymphoblastic leukemia

ABSTRACT

Compounds of formula (I) in the capacity of compounds with anti-tumor activity for the treatment of T-cell acute lymphoblastic leukemia (T-ALL).

FIELD OF THE INVENTION

The present description relates to new Notch inhibitor compounds for use in the treatment of T-cell acute lymphoblastic leukemia.

BACKGROUND OF THE INVENTION

Notch signaling is an inter-cellular communication system that plays a key role in regulating biological processes of primary importance, such as self-maintenance and stem cell differentiation in embryonic development and in homeostasis in different tissues of the adult organism.

In mammals, the Notch family comprises four trans-membrane receptors (Notch1-4), highly conserved from an evolutionary point of view, and five ligands (Jagged-1, -2, Delta-like-1, -3 and -4).

Notch signaling activation occurs through the interaction of the extracellular domain of a Notch receptor, expressed on the membrane of a cell receiving the signal, with a ligand present on the membrane of a signaling cell. Interaction with the ligand predisposes the Notch receptor to two consecutive proteolytic cuts, by the enzymatic action of the TACE complex (ADAM metalloprotease TNF-α converting enzyme) before, and of the gamma-secretase complex after, which culminate with the release of the active Notch intracellular domain (NICD), which moves into the nucleus and promotes the expression of specific target genes.

The constitutive activation of the pathway, due to mutations, gene amplifications or post-translational changes to Notch receptors, is directly related to the development, progression, angiogenesis, and poor prognosis in a large number of oncologic pathologies, including T-cell acute lymphoblastic leukemia (T-ALL).

Therefore, one of the objectives of the research, aimed at developing innovative therapies for curing T-ALL, is the pharmacological inhibition of Notch signaling.

In this context, to date, the most promising approach and the examination of several clinical trials involves blocking the proteolytic cut of the Notch receptor that leads to the release of the activated domain through treatment with small molecules of gamma-secretase inhibitors (GSIs). Unfortunately, as revealed by clinical studies, potential clinical applications of GSIs in anti-tumor therapies are limited by primary resistance and/or side effects associated with the treatments. In particular, it has been shown that exposure to GSIs often accompanies the onset of metaplasia of the goblet cells of the intestine.

A second strategy, alternative to the use of GSIs, involves the use of selectively directed monoclonal antibodies against Notch receptors and/or ligands, but this approach also has intrinsic limits. The efficacy of the action of ligand-competitive antibodies is closely related to the expression levels of the receptors and their ligands, and the different affinity of the four Notch receptors for the respective ligands. Furthermore, the therapeutic use of antibodies may be ineffective in T-ALL subgroups in which the signaling is constitutively activated due to chromosomal translocations or Notch gene mutations.

Given the high number of diseases and tumors associated with the deregulation of the Notch pathway, it is even more necessary to develop new, efficient, specific and safe therapies directed at the inhibition of this signaling in order to effectively counteract resistance, recurrence and metastatization phenomena in different solid and hematologic tumors including T-ALL.

SUMMARY OF THE INVENTION

Taking these considerations into account, there is a need for innovative therapeutic solutions that effectively treat T-cell acute lymphoblastic leukemia.

In accordance with the present invention, the aforesaid object is achieved thanks to the solution specifically referred to in the attached claims, which form an integral part of the present description.

One embodiment of the present invention refers to compounds of formula (I) for use as compounds with anti-tumor activity for the treatment of T-cell acute lymphoblastic leukemia (T-ALL)

wherein

X and Y are carbon atoms bound by a single or double bond having, independently, an E or Z configuration;

R_(1′) is hydrogen, halogen, OR_(A), C(═O)R_(A), C(═O)OR_(A), OC(═O) R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), N(R_(A))₂, NHC(═O)R_(A), C(═O)N(R_(A))₂, or C(R_(A))₃;

R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OR_(B); C(═O)R_(B); C(═O)OR_(B); OC(═O)R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B))₂; NHC(═O)R_(B); C(═O)N(R_(B))₂; C(R_(B))₃; a linear or branched, saturated or unsaturated C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

wherein at each occurrence R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

and pharmaceutically acceptable salts thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in detail, by way of non-limiting example, with reference to the attached figures, wherein:

FIG. 1. Chalcone C inhibits endogenous Notch signaling in T-ALL DND41 cells. Protein expression of the activated domain of Notch1 (N1VAL), of the intracellular domain of Notch3 (N3ICD) and of β-actin in DND41 cells in response to 36 hours of treatment at increasing concentrations of eight molecules (designated as A-H) representative of a library of about 1000 different compounds.

FIG. 2. General scheme for the synthesis of compounds 1-17. Claisen-Schmidt condensation was used to prepare the chalcone scaffold. The compounds 5a, 7a-8a, 11a and 14a-17a were subsequently deprotected to form their respective chalcones.

FIG. 3. Compound 8 is a potent inhibitor of Notch signaling in DND41 cells. Protein expression levels of N1VAL, N3ICD and β-actin in DND41 cells in response to 36 hours of treatment at increasing concentrations of 12 synthetic derivatives of chalcone C (named 1, 2, 3, 4, 5, 5a, 6a, 7, 7a, 8, 8a and 9).

FIG. 4. The synthetic derivatives of compound 8 reveal low levels of inhibitory activity of Notch signaling. Protein expression levels of N1VAL, N3ICD and β-actin in DND41 cells in response to 36 hours of treatment at increasing concentrations of compound 8 and its 14 synthetic derivatives (named 8b, 10, 11, 11a, 12, 14, 14a, 15, 15a, 16a, 17 and 17a).

FIG. 5. Compound 8 is the most potent inhibitor of Notch signaling among the synthetic derivatives of C taken into consideration (A) Western blot representatives (B) and relative densitometric quantifications (OD) of N1VAL, N3ICD and β-actin expression levels in DND41 cells in response to 36 hours of treatment with 2.5 μM of compounds 8, 16 or 17. The data shown in the graph represent the means values±standard deviations of three independent experiments. *P<0.05; **P<0.01; n.s. not significant.

FIG. 6. Compound 8 represses Notch signaling in cellular contexts of T-ALL (A) Protein expression levels of N1VAL and β-actin in KOPTK1 cells and in HaCat cells and protein expression of N3ICD and β-actin in TALL-1 cells in response to 36 hours of treatment at increasing concentrations of compound 8 (B) Gene expression levels of DELTEX1 (DTXI), HES1 and c-MYC in response to 36 hours of exposure to 2.5 μM of compound in KOPTK1 and DND41 cells, and in response to 36 hours of exposure to 1 μM of compound 8 in TALL-1 cells. The data shown represent the mean values of three independent experiments, standardized with respect to GAPDH expression±standard deviations.

FIG. 7. Graphical representation of the SAR of the chalcone derivatives as Notch inhibitors in T-ALL. Analysis of the results obtained from the biological tests allowed identification of three structural levels for the SAR: ring A, ring B and the α,β-unsaturated carbonyl system of the chalcone scaffold.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, there are numerous specific details to provide a thorough understanding of the embodiments. The embodiments may be implemented, in practice, without one or more of the specific details, or with other methods, components, materials, etc. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid obscuring certain aspects of the embodiments.

Throughout the present specification, the reference to “an embodiment” or “embodiment” means that a particular configuration, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of expressions “in a certain embodiment” or “in an embodiment” in various points throughout this specification does not necessarily always refer to the same embodiment. Moreover, the particular details, structures or characteristics can be combined in any suitable way in one or more embodiments.

The headings used here are used merely for convenience, and do not interpret the object or meaning of the embodiments.

In recent years, scientific and industrial interest has been progressively increasing in relation to small naturally-occurring molecules, bio-pharmacologically active in various pathological contexts including neoplastic diseases. In this context, in addition to all the molecules proposed as gamma-secretase inhibitors, various naturally-occurring molecules have been proposed as potentially new anti-tumor agents capable of suppressing Notch signaling.

In the present study, a library of about one thousand naturally-occurring compounds, isolated from plants known for their use in traditional medicine, and their chemical derivatives, were grouped into clusters according to a chemo-informatics approach.

The clustering of the library according to this method allowed the obtainment of groups of chemically and pharmacologically similar molecules, for each of which a representative molecule (A-H) has been identified, illustrated in Table 1.

In order to detect small molecules able to modulate the Notch signal transduction pathway, the effects on the endogenous activation of Notch signaling and on cell proliferation in stabilized human lines of T-ALL were evaluated, known to be sensitive to the block of Notch signaling for each representative molecule of each of the eight clusters (A-H).

The cross-analysis of the results obtained from biochemical and functional assays indicated the molecule 3,4,2′,4′-tetrahydroxychalcone (butein, C) as a new and potent inhibitor of Notch signaling able to significantly inhibit cell proliferation at low concentrations. In this regard, the inventors of the present application have verified that short exposure times to the molecule C significantly repress both the proliferation and the endogenous activation of the Notch1 receptor starting from a concentration between 5 μM and 10 μM, with a dose-dependent effect in human T-ALL cell lines.

In order to enhance the activity and selectivity of action of butein (C), the present inventors have designed a number of structural analogues of butein, which have been synthesized and tested in vitro.

Analysis of the results obtained from biochemical and functional assays has shown that these compounds exhibit a good inhibitory capacity of Notch signaling and proliferation compared to butein itself, so that these compounds present a pharmacological potential for treating T-cell acute lymphoblastic leukemia.

In one embodiment, the present description concerns compounds of formula (I) as compounds with anti-tumor activity for the treatment of T-cell acute lymphoblastic leukemia (T-ALL)

wherein

X and Y are carbon atoms bound by a single or double bond having, independently, an E or Z configuration;

R_(1′) is hydrogen, halogen, OR_(A), C(═O)R_(A), C(═O)OR_(A), OC(═O) R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), N(R_(A))₂, NHC(═O) R_(A), C(═O) N(R_(A))₂, or C(R_(A))₃;

R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OR_(B); C(═O)R_(B); C(═O)OR_(B); OC(═O)R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B))₂; NHC(═O) R_(B); C(═O) N(R_(B))₂; C(R_(B)) 3; a linear or branched, saturated or unsaturated C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

wherein, at each occurrence, R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

and pharmaceutically acceptable salts thereof.

In one or more embodiments of the invention of the present description, X and Y are carbon atoms bound by a double bond in the compounds of formula (I).

In one or more embodiments of the invention subject of this description R_(1′) is hydrogen, halogen, OR_(A), OC(═O) R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), C(R_(A))₃; R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OROR_(B); C(═O)R_(B); C(═O)OR_(B); OC(═O)R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B))₂; NHC(═O)R_(B); C(═O)N(R_(B))₂; C(R_(B))₃; R_(A) and R_(B), at each occurrence, are independently selected from: hydrogen; a saturated or unsaturated aliphatic, linear or branched C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen and sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group.

In one or more embodiments of the invention subject of the present description R_(1′) is hydrogen, halogen, OR_(A), OC(═O) R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), C(R_(A))₃; R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: a saturated or unsaturated, linear or branched C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen and sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group, and R_(A) assumes the meaning indicated above.

In one embodiment of the invention subject of the present description, X and Y are carbon atoms bound by a double bond with an E or Z configuration; R_(1′) is OR_(A); R_(2′) is hydrogen; R_(3′), R₁, R₂, are the same or different and independently selected from: hydrogen and OR_(B); R₃ is OR_(B); and R_(A) and R_(B), at each occurrence, are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group, preferably a linear or branched, saturated or unsaturated C₁₋₃ aliphatic group; a C₅₋₇ heterocyclic group.

A preferred embodiment of the invention subject of the present description concerns a compound selected from:

-   -   2′,3,4,4′-tetramethoxychalcone (1)     -   2′-hydroxy-3,4,4′-trimethoxychalcone (2)     -   2′-hydroxy-4,4′-dimethoxychalcone (3)     -   2′,4,4′-trimethoxychalcone (4)     -   2′-hydroxy-4,4′-dimethoxy-3-(tetrahydropyran-2-yloxy) chalcone         (5a)     -   2′,3-dihydroxy-4,4′-dimethoxychalcone (5)     -   2′-hydroxy-3,4-dimethoxy-4′-(tetrahydropyran-2-yloxy)chalcone         (6a)     -   2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone         (7a)     -   2′,4-dihydroxy-3,4′-dimethoxychalcone (7)     -   2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a)     -   2′,4-dihydroxy-4′-methoxychalcone (8)     -   2′,4-dihydroxy-4′-methoxydihydrochalcone (8b)     -   2′-hydroxy-4′-methoxychalcone (9)     -   2′-hydroxy-3,4′-dimethoxychalcone (10)     -   2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a)     -   2′,3-dihydroxy-4′-methoxychalcone (11)     -   2,2′-dihydroxy-4′-methoxychalcone (12)     -   2′-hydroxy-2,4′-dimethoxychalcone (13)     -   2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a)     -   2′,4-dihydroxychalcone (14)     -   2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a)     -   4-hydroxy-2′-methoxychalcone (15)     -   2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a)     -   4-hydroxy-2′,4′-dimethoxychalcone (16)     -   4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a)     -   4-hydroxy-4′-methoxychalcone (17).

In an additional embodiment, the present description relates to a pharmaceutical composition comprising at least one compound of formula (I), as defined above, and at least one pharmaceutically acceptable excipient or vehicle.

In a different embodiment, the present description relates to compounds of formula (I)

wherein

X and Y are carbon atoms bound by a single or double bond having, independently, an E or Z configuration;

R_(1′) is hydrogen, halogen, OR_(A), C(═O) R_(A), C(═O) OR_(A), OC(═O) R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), N(R_(A))₂, NHC(═O)R_(A), C(═O)N(R_(A))₂, or C(R_(A))₃;

R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OR_(B); C(═O) R_(B); C(═O) OR_(B); OC(═O) R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B)) 2; NHC(═O) R_(B); C(═O) N(R_(B)) 2; C(R_(B))₃; a linear or branched, saturated or unsaturated C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

wherein, at each occurrence, R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;

and relative salts, preferably pharmaceutically acceptable salts.

In general, the data of the present invention propose butein and synthetic chalcones of formula (I), butein analogues, as inhibitors of Notch signaling, and emphasize the efficacy of compound 8 as a new potential antitumor agent that blocks Notch signaling. In this regard, short-term treatment with compound 8 represses cell proliferation, protein expression of activated domains of Notch1 and Notch3 receptors, and the gene expression of several known transcriptional targets of the Notch pathway at lower concentrations than the molecule C in different T-ALL cellular models.

In this regard, it should be noted that in European patent application EP 2606884, small molecule inhibitory compounds of Notch are disclosed, although these compounds exhibit inhibitory activity comparable to that of compound 8, the latter has a significantly lower molecular weight. Given that the efficiency of a candidate drug is given by the relationship between the biological activity and the molecular weight (or the number of heavy atoms), compound 8 is considerably more efficient, being further validated by SAR studies. The patent application US-A-2015/0175548 discloses a molecule similar to nifedipine, with comparable anti-proliferative activity, albeit slightly less efficient, to that of compound 8. It should be noted that nifedipine is a calcium channel blocker, with effects on cardiac activity, so that its use in therapy is doubtful given the potential relevance of the side effects it may cause, particularly on the heart.

In a recent study, the molecule Xanthohumol has been described as a Notch signaling inhibitor and apoptosis promoter in hepatocarcinoma cells with IC₅₀, on average, between 10 and 15 μM (Kunnimalaiyaan et al., 2015). Compound 8, although structurally related to the molecules described by Kunnimalaiyaan and colleagues, was shown to be significantly more active. It should be noted that, in addition to that reported, in the screening carried out by the present inventors, the chalcones of formula (I) prenylated in ring A, although the prenylation position was different from that of the compound being disclosed, did not show any inhibitory activity of Notch (4-OH-Isocordoin).

Results

Butein: Naturally-Occurring Chalcone as an Inhibitor of the Notch Signal Transduction Pathway

To focus attention on a relatively small, manageable number of molecules of the library of natural products, only the molecules most representative of the eight most abundant clusters were considered for in vitro tests. For this purpose, a diversity-oriented random selection (DORS) approach was used of the compounds based on a clustering algorithm that is based on the substructure and molecular fingerprint similarity (Stahl and Mauser, 2005). Representative molecules of the eight clusters are shown in Table 1.

TABLE 1 Structure and inhibitory activity of the natural compounds A-H. The values of IG₅₀ were calculated for 36-hour treatments in DND41 cells. The reported values represent the mean of triplicate experiments ± S.D. Compound Chemical structure IG50 S.D. (μg) A

>50 B

13.89  2.70 C

7.79 1.73 D

>50 E

>50 F

>50 G

>50 H

22.64  1.89

In order to identify new naturally-occurring molecular agents able to modulate Notch signaling, the effects on protein expression of the activated domain of Notch1 (N1VAL), and of the intracellular domain of Notch3 (N3ICD), were evaluated in DND41 cells through Western blotting assays, following treatment for 36 hours with increasing concentrations (0, 1, 5, 10, 20, 50 μM) of the eight molecules (A-H) previously selected. Functional biochemical screening was performed on T-ALL DND41 cells because they are notoriously sensitive to the block of Notch signaling, and characterized by the constitutive and ligand-independent activation of the Notch1 pathway and by the high expression of Notch3. This makes this cell line a useful experimental model for screening putative Notch inhibitors.

Among the eight molecules considered, molecule C revealed the highest inhibitory activity against Notch signaling, as shown by the decreased expression of N1VAL and N3ICD at concentrations ranging from 5 μM to 10 μM (FIG. 1). On the other hand, treatments with the molecules D, E, F and G did not significantly modulate the expression of N1VAL, while A, B and H reduce its expression at very high concentrations (between 20 μM and 50 μM) (FIG. 1).

In order to evaluate the biological implications of the compounds, their effect on cell proliferation/vitality was tested by determining the relative concentrations of growth inhibition (IG₅₀) by means of the MTS cellular assay. Consistent with the high inhibitory activity of Notch, exposure to molecule C dramatically reduces cell proliferation in DND41 cells at concentrations comparable to those sufficient to inhibit Notch signaling (IG₅₀ of 7.79±1.73 μM) (Table 1). Conversely, compounds B and H show a low anti-proliferative activity with IG₅₀ values of 13.89±2.70 μM and 22.64±1.89 μM, respectively, while the molecules A, D, E, F and G do not significantly affect cell proliferation at doses of up to 50 μM. Overall, cross-analysis of the screening data described above indicates that among all the natural compounds considered, chalcone C (butein) is the most potent inhibitor of Notch signaling and cell proliferation in T-ALL cells.

Design and Synthesis of Butein Derivatives

Results from the biological tests have suggested the promising role of the chalcone scaffold in modulating the Notch signaling pathway. Given that molecule C emerged from the first screening as a promising hit, a second generation of chemical derivatives (Table 2) was designed and synthesized in order to increase the biological activity, to remove the catecholic group (Schweigert et al., 2001) that is very sensitive to oxidation reactions, and to outline the structure-activity relationships (SAR). The general synthetic strategy used to prepare chalcones is based on the Claisen-Schmidt condensation (FIG. 2) (Sogawa et al., 1994).

TABLE 2 Structure and inhibitory activity of synthetic derivatives of chalcone C (1-17). The IG₅₀ values were calculated for 36-hour treatments in DND41 cells. The reported values represent the mean of triplicate experiments ± S.D. (II)

Compound R_(1′) R_(3′) R₁ R₂ R₃ X—Y^((a)) IG₅₀ ± S.D. (μM)  1 OCH₃ OCH₃ H OCH₃ OCH₃ CH═CH 15.04 ± 3.04   2 OH OCH₃ H OCH₃ OCH₃ CH═CH 30.96 ± 5.98   3 OH OCH₃ H H OCH₃ CH═CH 47.50 ± 1.41   4 OCH₃ OCH₃ H H OCH₃ CH═CH 14.41 ± 2.56   5a OH OCH₃ H OTHP OCH₃ CH═CH >50  5 OH OCH₃ H OH OCH₃ CH═CH 36.24 ± 10.61  6a OH OTHP H OCH₃ OCH₃ CH═CH >50  7a OH OCH₃ H OCH₃ OTHP CH═CH 24.44 ± 1.76   7 OH OCH₃ H OCH₃ OH CH═CH 33.10 ± 1.89   8a OH OCH₃ H H OTHP CH═CH 48.52 ± 3.42   8b OH OCH₃ H H OH CH₂—CH₂ >50  8 OH OCH₃ H H OH CH═CH 1.92 ± 0.14  9 OH OCH₃ H H H CH═CH 11.11 ± 0.59  10 OH OCH₃ H OCH₃ H CH═CH 21.32 ± 1.72  11a OH OCH₃ H OTHP H CH═CH 17.35 ± 1.2  11 OH OCH₃ H OH H CH═CH 13.62 ± 1.76  12 OH OCH₃ OH H H CH═CH 14.23 ± 0.58  13 OH OCH₃ OCH₃ H H CH═CH 21.76 ± 1.78  14a OH H H H OTHP CH═CH 48.52 ± 3.42  14 OH H H H OH CH═CH 16.47 ± 0.90  15a OCH₃ H H H OTHP CH═CH 31.52 ± 1.46  15 OCH₃ H H H OH CH═CH 16.82 ± 2.71  16a OCH₃ OCH₃ H H OTHP CH═CH 32.57 ± 0.92  16 OCH₃ OCH₃ H H OH CH═CH 13.82 ± 0.61  17a H OCH₃ H H OTHP CH═CH 28.76 ± 0.29  17 H OCH₃ H H OH CH═CH 19.50 ± 0.56 

Compound 8 is a Potent Inhibitor of Notch and Proliferation in T-ALL Cells.

In order to investigate the activity and selectivity of action of the 12 synthetic derivatives of butein, and following the screening scheme described in the first design phase, the efficacy of these molecules was analyzed by verifying the effects of 36 hours of treatment at increasing doses on the activation of Notch signaling and on the proliferation in DND41 cells.

Treatments with compound 8 inhibit the expression of Notch1 and Notch3 activated domains at lower concentrations than butein (doses between 1 μM and 5 μM) (FIG. 3). Conversely, all the other 11 synthetic derivatives modulate the expression levels of the two receptor domains at higher concentrations (FIG. 3). In support of the high inhibitory activity of Notch, cell proliferation assays in response to increasing doses of the synthetic compounds demonstrated that compound 8 is the most potent repressor of proliferation. Treatments with compound 8 repress proliferation with IG₅₀=1.92 μM±0.14 μM, while all the other chemical derivatives present anti-proliferative activities that are 10 to 20 times weaker, as demonstrated by IG₅₀ values greater than 11 μM (Table 1). Given the high power of action at low micromolar concentrations of compound 8, subsequent functional and biological comparison analyses between compound 8 and the additional 14 compounds illustrated in Table 2 were carried out by adding two intermediate concentrations (0.5 μM and 2.5 μM) in dose-response assays (0, 0.5, 1, 2.5, 5, 10, 20, 50 μM). Among the 14 compounds of Table 2, only molecules 16 and 17 showed inhibitory activity of Notch signaling in a range of concentrations comparable to those disclosed for compound 8 (at doses of 2.5 μM) (FIG. 4). The subsequent comparative analysis of the effects of 36 hours of treatment with compounds 8, 16 and 17 on the protein expression of N1VAL and N3ICD finally confirmed compound 8 as the most potent Notch inhibitor (FIG. 5). In addition, compound 8 is the most effective antiproliferative agent compared to all the synthetic derivatives tested, including 16 and 17, which reveal IG₅₀ values greater than 13 μM (Table 2).

Overall, the data obtained in the experiment described above propose compound 8 as the most promising Notch blocking agent among all the molecules tested, and in order to exclude possible specific cell line effects, analysis was also carried out on additional cell lines. As confirmation of its efficacy on the inhibition of Notch signaling, 36 hours of treatment with compound 8 reduced N1VAL expression levels in KOPTK1 cells and N3ICD in TALL-1 cells, in a dose-dependent manner (FIG. 6A). The KOPTK1 cell line is characterized by constitutive Notch1 activation, due to gene mutations of Notch1, while the TALL-1 cell line, due to mutations of the Notch3 gene, has constitutively active signaling of the Notch3 receptor.

In line with the block of signaling, treatment with compound 8 in DND41, KOPTK1 and TALL-1 cells significantly reduces the expression of known Notch gene targets such as DELTEX1, HES1e and c-MYC (FIG. 6B). In addition, in the same lines, compound 8 drastically inhibits cell proliferation with IC₅₀=0.91±0.06 μM in KOPTK1 cells and with IC₅₀=0.29±0.02 μM in TALL-1 cells.

Conversely, exposure to compound 8 does not significantly influence the proliferation of immortalized non-tumor lines of HaCaT keratinocytes (IC₅₀=48.61±8.06 μM), in which Notch acts as an oncosupressor. Confirming instead the Notch blocking activity, treatment with compound 8 in the same cells significantly reduces the expression of the activated domain of Notch1 starting from concentrations of 2.5 μM (FIG. 6A).

Structure-Activity Relationships (SARs) of Chalcone Derivatives

Biological analyzes of the natural chalcone C and of the compounds of formula (I) highlight compound 8 as the most active Notch inhibitor in T-ALL. The SAR was processed and graphically represented (FIG. 7), based on three structural levels of the chalcone base skeleton: ring A, ring B and the α,β-unsaturated carbonyl system.

Regarding ring A, methylation of the hydroxyl group at position 2′ improves the inhibitory effect on cell proliferation, only when ring B is not replaced by hydroxyl groups at position 4. Under these conditions, the presence of the methoxyl group at position 4′ provides a greater activity with respect to the steric mole of the tetrahydropyranyl protecting group. Therefore, it is apparent from the structure of compound 8 that the hydroxylic substitutions act synergically at positions 2′ and 4 of the chalcone scaffold. Based on this evidence, the single replacement on ring A (14, 15 and 17) at different positions reduces biological activity with respect to the rings with double replacement at position 2′ and 4′ (8 and 16). In addition, single-replacement derivatives have shown a comparable inhibitory effect on cell proliferation, although methylation of the hydroxyl group at position 4′ dramatically reduces the expression levels of N1VAL and N3ICD with respect to compound 8, unlike that observed for chalcones with a single-replacement at position 2′ (14 and 15).

In particular, the activity of chalcone derivatives seems to be significantly dependent on the replacement of ring B. Indeed, comparing the chalcones having the same ring A, the hydroxyl group improves the biological activity, particularly when inserted at position 4, playing a key role in reducing both cell proliferation activity and Notch expression (8).

Finally, reducing the double bond of the α,β-unsaturated carbonyl system completely abolishes the biological efficacy, suggesting that the reduced molecular flexibility required to ensure the distance between the phenyl rings A and B is more suitable for inducing Notch inhibition.

Materials and Methods

Chemoinformatics

A clustering algorithm similar to that previously developed by Stahl and Mauser (Stahl and Mauser, 2005) was generated and used, exploiting the modularity and versatility of the Python scripting language (OpenEye Python Toolkit [OpenEye Toolkits 2015. OpenEye Scientific Software, Santa Fe, N. Mex. http://www.eyesopen.com]). The algorithm was then used to cluster the molecules of the in-house library of naturally-available compounds. A threshold value of 0.6 for the Tanimoto comparison of the maccs166-type fingerprints, while a threshold value of 0.8 was used to compare the Raymond's score (Raymond et al., 2002) during the analysis and comparison of the substructures of the various molecules (Stahl and Mauser, 2005).

Characterization of the Naturally-Occurring Compounds A-H

All the tested compounds A-H come from the library of natural products of the laboratory of Prof. Botta.

The chemical identity of the compounds tested is known and was verified by Nuclear Magnetic Resonance (NMR), the results obtained were in accordance with those reported in the literature.

The purity of compounds A, B, E and F was greater than 95% and was analyzed using reverse phase HPLC, the chromatographic conditions are reported below.

Compound A (taxifolin or (2R,3R)-2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-2,3-dihydrochromen-4-one) NMR analysis was consistent with that reported in the literature (Yang et al., 2015).

Compound B (4-hydroxy-isocordoin or (E)-1-[2,4-dihydroxy-3-(3-methylbut-2-enyl)phenyl]-3-(4-hydroxyphenyl) prop-2-en-1-one) NMR analysis was consistent with that reported in the literature (Monache et al., 1974).

Compound C (butein or (E)-1-(2,4-dihydroxyphenyl)-3-(3,4-dihydroxyphenyl)prop-2-en-1-one) (Chokchaisiri et al., 2009) was purchased from Sigma-Aldrich (487-52-5), and was used without further modifications.

Compound D (xantotoxin or 9-methoxyfuran[3,2-g]chromen-7-one (Compagnone and Rodriguez, 1993; Rashid et al., was purchased from Sigma-Aldrich (298-81-7), and was used without further modifications.

Compound E (columbianetin or (8R)-8-(2-hydroxypropane-2-yl)-8,9-dihydrofuran[2,3-h]chromen-2-one) NMR analysis was consistent with that reported in the literature (Cuca LE and Delle Monache, 1998).

Compound F (1-hydroxy-7-methoxy-9H-xanthen-9-one) NMR analysis was consistent with that reported in the literature (Delle Monache et al., 1983).

Compound G (usnic acid or 2,6-diacetyl-7,9-dihydroxy-8,9b-dimethyldibenzofuran-1,3-dione) (Studzinska-Srokaal et al., 2015) was purchased from Sigma-Aldrich (7562-61-0), and was used without further modifications.

Compound H (galangin or 3,5,7-trihydroxy-2-phenylchromen-4-one) (thong et al.) was purchased from Sigma-Aldrich (548-83-4), and was used without further modifications.

Synthesis Methods

All the reagents are commercially available and were used without further purification.

Silica gel (230-400 mesh) was used for purification by column gravity chromatography. All reactions were monitored by thin layer chromatography (TLC) and F254 fluorescence silica gel plates (Sigma-Aldrich 99569) were used. Melting points were determined with a Buchi Melting Point B-454 apparatus. The spectra ¹H and ¹³C NMR were registered using an Ultra Shield™ Bruker 400 instrument (400 MHz for ¹H NMR and 100 MHz for ¹³C NMR) using tetramethylsilane (TMS) as a standard. Chemical shifts are reported in parts per million (ppm). Multiplicities were reported as follows: singlet (s), doublet (d), triplet (t) and multiplet (m). Mass spectrometry was performed with the Thermo Finnigan LXQ linear ion trap mass spectrometer, equipped with electrospray ionization (ESI). High resolution mass spectra (HR-MS) were recorded with a Bruker BioApex Fourier transform ion cyclotron resonance (FT-ICR).

General Method for the Protection of 3- and 4-hydroxybenzaldehyde as Tetrahydropyranil Ethers.

3- or 4-hydroxybenzaldehyde (16 mmol) and the pyridinium p-toluene-sulfonate (0.40 mmol) (Sigma-Aldrich 232238) were solubilized in CH₂Cl₂ (dichloromethane) (75 ml). Dissolution of the reagents was carried out by magnetic stirring and, thereafter, a solution of 3,4-dihydro-a-pyran (2.23 ml, 0.5 mmol) (Sigma-Aldrich 37350) in CH₂Cl₂ (75 ml) was slowly added. The reaction was maintained with stirring at room temperature for about 24 hours; a series of washes was then carried out with distilled water, dehydration was carried out with Na₂SO₄ and the solvents were evaporated under vacuum. The residue was purified on a flash chromatography column using an eluent mixture of n-hexane:EtOAc=9:1 (v/v), to obtain the corresponding tetrahydropyranyloxybenzaldehyde (precursor of 5a, 7a, 8a, 11a, 14a, 15a, 16a, 17a).

General Procedure for the Protection of 4′-hydroxyacetophenone as Tetrahydropyranyl Ether.

4′-hydroxyacetophenone (16 mmol) and the pyridinium p-toluenesulfonate (0.40 mmol) were solubilized in CH₂Cl₂ (75 mL). Dissolution of the reagents was carried out by magnetic stirring and, thereafter, a solution of 3,4-dihydro-a-pyran (2.23 ml, 0.5 mmol) in CH₂Cl₂ (75 ml) was slowly added. The reaction was maintained with stirring at room temperature for about 24 hours; a series of washes was then carried out with distilled water, dehydration was carried out with Na₂SO₄ and the solvents were removed under vacuum. The residue was purified on a flash chromatography column using an eluent mixture of n-hexane:EtOAc=9:1 (v/v), to obtain the corresponding tetrahydropyranyloxyacetophenone.

General Procedure for the Claisen-Schmidt Reaction

Barium hydroxide octahydrate [Ba(OH)₂.8H₂O] was slowly added to a solution of the corresponding acetophenone (0.01 mmol) and the corresponding benzaldehyde (0.01 mmol) in EtOH (ethanol). The reaction was stirred, at room temperature for about 24 hours and then concentrated under vacuum. Subsequently, distilled water was added, the mixture was neutralized with 2N HCl and extracted with EtOAc (ethyl acetate). The organic fraction was dehydrated with Na₂SO₄ and the solvents were then removed under vacuum. The residue was purified on a flash chromatography column using an eluent mixture of n-hexane:EtOAc=9:1 (v/v) to obtain the corresponding chalcone 1-4, 9-10, 12-13, 5a-8a, 11a, 14a-17a.

General Procedure for Deprotection of Chalcones

The protected chalcones 5a, 7a-8a, 11a, 14a-17a (0.25 mmol) and p-toluenesulfonic acid (0.03 mmol) were solubilized in MeOH (20 ml). The reaction was stirred, at room temperature, for about 24 hours and the solvent was removed under vacuum. Subsequently, distilled water was added, the mixture was neutralized with 5% NaHCO₃ and extraction with EtOAc was carried out. The organic fraction was isolated, dehydration was carried out with Na₂SO₄ and the solvents were then removed under vacuum. The residue was purified on a flash chromatography column using an eluent mixture of n-hexane:EtOAc=9:1 (v/v) to obtain the corresponding chalcone 5, 7-8, 11, 14-18.

Catalytic Hydrogenation of 8

Inside the reaction tube, two empty/nitrogen cycles were performed, and then compound 8 (100 mg, 0.37 mmol) was placed with 10% Pd/C (98 mg) in EtOAc (10 mL) at room temperature, at 1 atm pressure of H₂ for 24 hours. The reaction mixture was filtered through a membrane filter (Millipore, Millex-LH, 0.45 mm) and the filtrate was concentrated to obtain compound 8b with a quantitative yield.

Characterization of the Compounds of Table 2 2′3,4,4′-tetramethoxychalcone (1)

yellow solid (85% yield); pf 71.9-73.3° C. ¹H NMR (400 MHz, CDCl₃): δ 7.72 (H-6′, 1H, d), δ 7.61 (C_(β)H, 1H, d, J=16.0 Hz), δ 7.35 (C_(α)H—CO, 1H, d, J=16.0 Hz), δ 7.18 (H-6, 1H, dd, J=8.4 Hz e J=1.6 Hz), δ 7.11 (H-2, 1H, d, J=2.6 Hz), δ 6.87 (H-5, 1H, d, J=8.4 Hz), δ 6.56 (H-5′, 1H, dd, J=8.4 Hz and J=2.0 Hz), δ 6.50 (H-3′, 1H, d, J=2 Hz), δ 3.92 (OCH₃, 3H, s), δ 3.92 (OCH₃, 3H, s), δ 3.90 (OCH₃, 3H, s), δ 3.87 (OCH₃, 3H, s). ¹³C NMR (100 MHz, CDCl₃): δ 190.73, δ 163.94, δ 160.20, δ 150.97, δ 149.14, δ 142.43, δ 132.66, δ 128.44, δ 125.32, δ 122.61, δ 122.46, δ 111.12, δ 110.27, δ 105.09, δ 98.75, δ 55.97, δ 55.75, δ 55.53.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₉H₂₁O₅ 329.13852 (monoisotopic mass), found 329.13857; [M+Na]⁺ calculated C₁₉H₂₀O₅Na 351.12029 (monoisotopic mass), found 351.11879.

2′-hydroxy-3,4,4′-trimethoxychalcone (2)

yellow solid (50% yield); pf 157.8-158.3° C. ¹H NMR (400 MHz, CDCl₃): δ 13.54 (OH, 1H, s), δ 7.85 (C_(β)H, 1H, d, J=15.6 Hz,), δ 7.86 (H-6′, 1H, d), δ 7.44 (C_(α)H—CO, 1H, d, J=16.0 Hz), δ 7.25 (H-6, 1H, dd, J=8.1 Hz and J=6 Hz), δ 7.16 (H-2, 1H, d, J=2 Hz), δ 6.91 (H-5, 1H, d, J=8.4 Hz), δ 6.51-6.47 (H-3′ and H-5′, 2H, m), δ 3.97 (OCH₃, 3H, s), δ 3.94 (OCH₃, 3H, s), δ 3.86 (OCH₃, 3H, s). ¹³C NMR (100 MHz, CDCl₃): δ 191.80, δ 166.67, δ 166.08, δ 151.61, δ 149.31, δ 144.59, δ 131.13, δ 127.81, δ 123.33, δ 118.05, δ 114.14, δ 111.18, δ 110.26, δ 107.66, δ 101.06, δ 56.03, δ 55.59, δ 53.42.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₈H₁₉O₅ 315.12270 (monoisotopic mass), found 315.12313; [M+Na]⁺ calculated C₁₈H₁₈O₅Na 377.10464 (monoisotopic mass), found 337.10489.

2′-hydroxy-4,4′-dimethoxy chalcone (3)

yellow solid (25% yield); pf 133.4-134.2° C. ¹H NMR (400 MHz, CDCl₃): δ 13.56 (OH, 1H, s), δ 7.87 (C_(β)H, 1H, d, J=15.6 Hz,), δ 7.84 (H-6′, 1H, d, J=8 Hz), δ 7.62 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 7.47 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 6.95 (H-3 and H-5, 2H, d, J=8.8 Hz), δ 6.50-6.48 (H-3′ and H-5′, 2H, m); δ 3.87 (OCH₃, 3H, s); δ 3.86 (OCH₃, 3H, s). ¹³C NMR (100 MHz, CDCl₃): δ 191.90, δ 166.64, δ 166.05, δ 161.82, δ 144.28, δ 131.12, δ 130.37, δ 127.56, δ 117.85, δ 114.48, δ 114.17, δ 107.63, δ 101.07, δ 55.59, δ 55.44.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₄ 285.11214 (monoisotopic mass), found 285.11213; [M+Na]⁺ calculated C₁₇H₁₆O₄Na 307.09408 (monoisotopic mass), found 307.09413.

2,4,4′-trimethoxychalcone (4)

yellow solid (12% yield); pf 87.2-88.2° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 7.70 (H-2, H-6 and H-6′, 3H, m), δ 7.62 (C_(β)H, 1H, d, J=15.6 Hz,), δ 7.53 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.03 (H-3 and H-5, 2H, m), δ 6.71 (H-3′, 1H, d, J=2 Hz); δ 6.66 (H-5′, 1H, dd, J=8 Hz and J=2 Hz); δ 3.99 (OCH₃, 3H, s); δ 3.93 (OCH₃, 3H, s); δ 3.89 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 189.08, δ 164.23, δ 161.45, δ 160.47, δ 140.87, δ 132.21, δ 131.73, δ 129.89, δ 128.13, δ 125.12, δ 122.33, δ 114.34, δ 113.22, δ 105.70, δ 98.34, δ 55.32, δ 55.06, δ 54.85.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₈H₁₉O₄ 299.12779 (monoisotopic mass), found 299.12822; [M+Na]⁺ calculated C₁₈H₁₈O₄Na 321.10973 (monoisotopic mass), found 321.10938.

2′-hydroxy-4,4′-dimethoxy-3-(tetrahydropyran-2-yloxy) Chalcone (5a)

yellow solid (35% yield); pf 123.9-125.9° C. ¹H NMR (400 MHz, CDCl₃): δ 13.55 (OH, 1H, s), δ 7.83 (C_(β)H, 1H, d, J=15 Hz), δ 7.82 (H-6f, 1H, d, J=8 Hz), δ 7.47 (H-2, 1H, d, J=2 Hz), δ 7.42 (C_(α)H—CO, 1H, d, J=15.0 Hz), δ 7.28 (H-6, 1H, dd, J=8.4 Hz and J=1.6 Hz), δ 6.92 (H-5, 1H, d, J=8.4 Hz), δ 6.49-6.47 (H-3′ and H-5′, 2H, m), δ 5.47 (H-1″, 1H, m), δ 4.01 (H_(α)-5″, 1H, m), δ 3.91 (OCH₃, 3H, s), δ 3.86 (OCH₃, 3H, s), δ 3.65 (H_(β)-5″, 1H, m), δ 2.08-1.67 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 191.86, δ 166.64, δ 166.09, δ 148.94, δ 145.98, δ 144.34, δ 131.16, δ 128.51, δ 122.94, δ 118.48, δ 113.02, δ 110.61, δ 107.63, δ 101.11, δ 94.68, δ 62.94, δ 56.06, δ 55.58, δ 31.93, δ 30.89, δ 25.46, δ 19.76.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated for C₂₂H₂₅O₆ 385.16456 (monoisotopic mass), found 385.16486; [M+Na]⁺ calculated C₂₂H₂₄O₆Na 407.14651 (monoisotopic mass), found 407.14568.

2′,3-dihydroxy-4,4′-dimethoxychalcone (5)

yellow solid (quantitative yield); pf 161.6-164.0° C. ¹H NMR (400 MHz, DMSO-dd: δ 13.63 (OH, 1H, s), δ 9.30 (OH, 1H, s) δ 8.29 (H-6′, 1H, d, J=9.2 Hz), δ 7.82 (C_(ρ)H, 1H, d, J=15.2 Hz), δ 7.75 (C_(α)H—CO, 1H, d, J=16 Hz), δ 7.41 (H-2, 1H, d, J=1.6 Hz), δ 7.36 (H-6, 1H, dd, J=8.4 Hz and J=1.6 Hz), δ 7.04 (H-5, 1H, d, J=8.4 Hz), δ 6.59 (H-5′, 1H, dd, J=9.2 Hz and J=2.4 Hz), δ 6.54 (H-3′, 1H, d, J=2.4 Hz), δ 3.88 (OCH₃, 6H, s). ¹³C NMR (100 MHz, DMSO-d6): δ 192.28, δ 166.26, δ 166.20, δ 151.02, δ 147.19, 5145.22, δ 133.00, δ 128.01, δ 122.90, δ 118.88, δ 115.64, δ 114.40, δ 112.34, δ 107.72, δ 101.42, δ 56.19, δ 56.17.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₅ 301.10705 (monoisotopic mass), found 301.10709; [M+Na]⁺ calculated 323.08899 C₁₇H₁₆O₆Na 323.08899 (monoisotopic mass), found 323.08861.

2′-hydroxy-3,4-dimethoxy-4′-(tetrahydropyran-2-yloxy)chalcone (6a)

yellow solid (18% yield); pf 116.3-118.6° C. ¹H NMR (400 MHz, CDCl₃): δ 13.37 (OH, 1H, s), δ 7.85 (C_(β)H, 1H, d, J=15.2 Hz), δ 7.84 (H-6′, 1H, d, J=9.2 Hz), δ 7.44 (C_(α)H—CO, 1H, d, J=15.2 Hz), δ 7.25 (H-6, 1H, dd, J=8.4 Hz and J=1.6 Hz), δ 7.16 (H-2, 1H, d, J=1.6 Hz), δ 6.91 (H-5, 1H, d, J=8.4 Hz), δ 6.67 (H-3′, 1H, d, J=2.4 Hz), δ 6.60 (H-5′, 1H, dd, J=8.8 Hz and J=2.4 Hz), δ 5.51 (H-1″, 1H, t), δ 3.96 (OCH₃, 3H, s), δ 3.94 (OCH₃, 3H, s), δ 3.89-3.83 (H_(α)-5″, 1H, m), δ 3.66-3.61 (H_(β)-5″, 1H, m), δ 1.89-1.60 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 191.95, δ 166.21, δ 163.53, δ 151.60, δ 149.31, 5144.64, δ 131.12, δ 127.82, δ 123.34, δ 118.10, δ 114.82, δ 111.19, δ 110.28, δ 108.45, δ 104.28, δ 96.17, δ 62.24, δ 56.03, δ 30.01, δ 25.00, δ 18.55.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₂H₂₅O₆ 385.16456 (monoisotopic mass), found 385.16512; [M+Na]⁺ calculated C₂₂H₂₄O₆Na 407.14651 (monoisotopic mass), found 407.14554.

2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (7a)

yellow solid (20% yield); fp 90.5-93.0° C. ¹H NMR (400 MHz, CDCl₃): δ 13.37 (OH, 1H, s), δ 7.84 (C_(β)H, 1H, d, J=15.2 Hz), δ 7.84 (H-6′, 1H, d, J=9.2 Hz), δ 7.44 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.23 (H-6, 1H, dd, J=8.4 Hz and J=1.6 Hz), δ 7.18-7.16 (H-2 and H-5, 2H, m), δ 6.50-6.48 (H-3′ and H-5′, 2H, m), δ 5.49 (H-1″, 1H, m), δ 3.97 (H_(α)-5″, 1H, m), δ 3.94 (OCH₃, 3H, s), δ 3.86 (OCH₃, 3H, s), δ 3.63 (H_(β)-5″, 1H, m), δ 2.05-1.57 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 191.81, δ 166.65, δ 166.06, δ 148.45, δ 146.83, δ 144.75, δ 131.11, δ 127.43, δ 123.49, δ 117.77, δ 114.94, δ 114.14, δ 110.20, δ 107.65, δ 101.6, δ 94.68, δ 56.05, δ 55.59, δ 30.70, δ 25.46, δ 19.76.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₂H₂₅O₆ 385.16456 (monoisotopic mass), found 385.16469; [M+Na]⁺ calculated C₂₂H₂₄O₆Na 407.14651 (monoisotopic mass), found 407.14616.

2′,4-dihydroxy-3,4′-dimethoxychalcone (7)

yellow solid (quantitative yield); pf 135.3-139.2° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 13.58 (OH, 1H, s), δ 8.18 (OH, 1H, s), δ 8.00 (H-6′, 1H, d, J=8.8 Hz), δ 7.73 (C_(β)H, 1H, d, J=15.2 Hz), δ 7.68 (C_(α)H—CO, 1H, d, J=15.2 Hz), δ 7.41 (H-2, 1H, d, J=2 Hz), δ 7.21 (H-6, 1H, dd, J=1.6 Hz and J=8.4 Hz), δ 6.78 (H-5, 1H, d, J=8.4 Hz), δ 6.38 (H-5′, 1H, dd, J=2.4 Hz and J=9.2 Hz), δ 6.33 (H-3′, 1H, d, J=2.4 Hz), δ 3.81 (OCH₃, 3H, s), δ 3.76 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): 5 192.16, δ 166.75, δ 166.26, δ 149.84, δ 147.95, 5145.05, δ 131.84, δ 127.06, δ 124.20, δ 117.47, δ 115.35, δ 114.02, δ 111.22, δ 107.21, δ 100.80, δ 55.54, δ 55.20.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₅ 301.10705 (monoisotopic mass), found 301.10716; [M+Na]⁺ calculated C₁₇H₁₆O₅Na 323.08899 (monoisotopic mass), found 323.08904.

2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a)

yellow solid (quantitative yield); pf 120.8-123.4° C. ¹H NMR (400 MHz, CDCl₃): δ 13.54 (OH, 1H, s) 7.87 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.83 (H-6′, 1H, d, J=10.4 Hz), δ 7.61-7.59 (H-2 and H-6, 2H, m), δ 7.47 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.11-7.09 (H-3 and H-5, 2H, m), δ 6.50-6.48 (H-3′ and H-5′, 2H, m), δ 5.50 (H-1″, 1H, m), δ 3.89 (H_(α)-5″, 1H, m), δ 3.87 (OCH₃, 3H, s), δ 3.63 (H_(β)-5″, 1H, m), δ 2.03-1.67 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 191.93, δ 166.64, δ 166.07, 159.30, δ 144.32, 5131.14, δ 130.57, δ 130.21, δ 128.24, δ 118.10, δ 116.79, δ 116.02, δ 114.18, δ 107.63, δ 101.09, δ 96.18, δ 62.06, δ 55.58, δ 30.17, δ 25.10, δ 18.57.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated for C₂₁H₂₃O₅ 355.15400 (monoisotopic mass), found 355.15443; [M+Na]⁺ calculated for C₂₁H₂₂O₅Na 377.13594 (monoisotopic mass), found 377.13542.

2′,4-dihydroxy-4′-methoxychalcone (8)

yellow solid (resa 70%); pf 152.8-158.5° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 13.72 (OH, 1H, s), δ 9.08 (OH, 1H, s), δ 8.18 (H-6′, 1H, d, J=8.8 Hz), δ 7.88 (C_(β)H, 1H, d, J=15.2 Hz), δ 7.80 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.77 (H-2 and H-6, 2H, d, J=8.4 Hz), δ 6.95 (H-3 and H-5, 2H, dd, J=8.4 Hz), δ 6.55 (H-5′, 1H, dd, J=2.4 Hz and J=9.2 Hz), δ 6.48 (H-3′, 1H, d, J=2.4 Hz), δ 3.90 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 192.19, δ 166.72, δ 166.27, δ 160.20, δ 144.59, 5131.87, δ 130.99, δ 126.67, δ 117.36, δ 115.91, δ 114.04, δ 107.17, δ 100.84, δ 55.17.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₄ 271.09649 (monoisotopic mass), found 271.09629; [M+Na]⁺ calculated C₁₆H₁₄O₄Na 293.07843 (monoisotopic mass), found 293.07842.

2′,4-dihydroxy-4′-metoxydihydrochalcone (8b)

brown oil (yield 10%). ¹H NMR (400 MHz, (CDCl₃): δ 12.81 (OH, 1H, s), δ 7.63 (H-6′, 1H, d, J=9.6 Hz), δ 7.11 (H-3 and H-5, 2H, d, J=8.4 Hz), δ 6.77 (H-2 and H-6, 2H, d, J=8.4), δ 6.41 (H-3′ and H-5′, 2 H, m), δ 4.80 (OH, 1H, s), δ 3.83 (OCH₃, 3H, s), δ 3.20 (C_(α)H₂—CO, 2H, t, J=8 Hz), δ 2.98 (C_(β)H₂, 2H, t, J=8 Hz). ¹³C NMR (100 MHz, (CDCl₃): δ 164.98, δ 164.36, δ 131.98, δ 130.46, δ 128.50, 5114.35, δ 106.66, δ 99.91, δ 54.55, δ 38.92, δ 30.91, δ 28.68, δ 28.51, δ 21.68, δ 13.11, δ 0.00.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated for C₁₆H₁₇O₄ 273.11214 (monoisotopic mass), found 273.11180; [M+Na]⁺ calculated C₁₆H₁₆O₄Na 295.09408 (monoisotopic mass), found 295.09452.

2′-hydroxy-4′-methoxychalcone (9)

yellow solid (yield 87%); pf 107.5-107.8° C. ¹H NMR (400 MHz, CDCl₃): δ 13.43 (OH, 1H, s), δ 7.89 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.84 (H-6′, 1H, d, J=8.4 Hz), δ 7.67-7.65 (H-2 and H-6, 2H, m), δ 7.65 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.44-7.42 (H-3, H-4 and H-5, 3H, m), δ 6.51-6.48 (H-3′ and H-5′, 2H, m), δ 3.87 (OCH₃, 3H, s). ¹³C NMR (100 MHz, CDCl₃): δ 191.40, δ 166.27, δ 165.80, δ 143.95, δ 134.36, δ 130.78, δ 130.19, δ 128.53, δ 128.07, δ 119.90, δ 113.65, δ 107.31, δ 100.64, δ 55.14.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₃ 255.10157 (monoisotopic mass), found 255.10180; [M+Na]⁺ calculated C₁₆H₁₄O₃Na 277.08352 (monoisotopic mass), found 277.08343.

2′-hydroxy-3,4′-dimethoxychalcone (10)

yellow solid (yield 35%); pf 89.2-91.8° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 13.56 (OH, 1H, s), δ 8.21 (H-6′, 1H, d, J=8.8 Hz), δ 7.99 (C_(β)H, 1H, d, J=15.2 Hz,), δ 7.88 (C_(α)H, 1H, d, J=15.6 Hz), δ 7.46-7.38 (H-2, H-4 and H-5, 3H, m), δ 7.05 (H-6, 1H, dd, J=8 Hz and J=2 Hz), δ 6.55 (H-5′, 1H, dd, J=9.2 Hz and J=2.4 Hz), δ 6.50 (H-3′, 1H, d, J=2.4 Hz), δ 3.91 (OCH₃, 3H, s); δ 3.89 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): 5 192.16, δ 166.84, δ 166.57, δ 160.26, δ 144.24, 5136.36, δ 132.17, δ 129.94, δ 121.58, δ 120.96, δ 116.68, δ 113.97, δ 113.40, δ 107.41, δ 100.83, δ 55.26, δ 54.84.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₄ 285.11214 (monoisotopic mass), found 285.11230; [M+Na]⁺ calculated C₁₇H₁₆O₄Na 307.09408 (monoisotopic mass), found 307.09351.

2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a)

yellow solid (83.44% yield); pf 92.4-94.6° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 12.77 (OH, 1H, s), δ 7.45 (H-6′, 1H, d, J=8.8 Hz) δ 7.20 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.09 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 6.76 (H-2, 1H, s), δ 6.70 (H-4, 1H, d, J=8 Hz), δ 6.62 (H-5, 1H, t, J=8 Hz), δ 6.4 (H-6, 1H, dd, J=2.4 Hz and J=8.4 Hz), δ 5.78 (H-5′, 1H, dd, J=2.4 Hz and J=9.2 Hz), δ 5.72 (H-3′, 1H, d, J=2.4 Hz), δ 4.79 (H-1″, 1H, t, J=3.2 Hz), δ 3.13 (OCH₃, 3H, s), δ 3.12-3.06 (H_(α)-5″, 1H, m), δ 2.86-2.01 (H_(β)-5″, 1H, m), δ 1.22-0.82 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 192.14, δ 166.83, δ 166.57, δ 157.65, δ 144.18, δ 136.24, δ 132.20, δ 129.88, δ 122.39, δ 120.94, δ 118.81, δ 116.38, δ 113.97, δ 107.43, δ 100.82, δ 96.07, δ 61.57, δ 55.26, δ 30.12, δ 25.04, δ 18.64.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₁H₂₃O₅ 355.15400 (monoisotopic mass), found 355.15396; [M+Na]⁺ calculated C₂₁H₂₂O₅Na 377.13594 (monoisotopic mass), found 377.13506.

2′,4-dihydroxy-4′-methoxychalcone (11)

yellow solid (resa 10.7%); pf 174.6-177.8° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 12.71 (OH, 1H, s), δ 7.82 (OH, 1H, s), δ 7.38 (H-6′, 1H, d, J=8.8 Hz), δ 7.08 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.00 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 6.49 (H-2, H-4, H-5; 3H, m, J=8 Hz), δ 6.13 (H-6, 1H, dd, J=2 Hz and J=7.6 Hz), δ 5.73 (H-5′, 1H, dd, J=2.4 Hz and J=9.2 Hz), δ 5.65 (H-3′, 1H, d, J=2.4 Hz) δ 3.07 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): 5 192.18, δ 166.80, δ 166.54, δ 157.88, δ 144.38, 5136.37, δ 132.15, δ 129.98, δ 120.69, δ 120.33, δ 117.87, δ 115.27, δ 113.97, δ 107.39, δ 100.84, δ 55.26.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₄ 271.09649 (monoisotopic mass), found 271.09660; [M+Na]⁺ calculated C₁₆H₁₄O₄Na 293.07843 (monoisotopic mass), found 293.07868.

2,2′-dihydroxy-4′-methoxychalcone (12)

yellow solid (yield 4%); pf 159.9-164.0° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 13.70 (OH, 1H, s), δ 9.30 (OH, 1H, s), δ 8.33 (C_(β)H, 1H, d, J=15.6 Hz), δ 8.17 (H-6′, 1H, d, J=9.2 Hz), δ 8.03 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.89 (H-6, 1H, dd, J=1.6 Hz and J=8.4 Hz), δ 7.36-7.32 (H-4, 1H, m), δ 7.05 (H-3, 1H, dd, J=2.8 Hz and J=8 Hz), δ 6.98 (H-5, 1H, t, J=7.6 Hz), δ 6.59 (H-5f, 1H, dd, J=2.4 Hz and J=8.8 Hz,), δ 6.52 (H-3′, 1H, d, J=2.4 Hz), δ 3.93 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 193.73, δ 192.54, δ 166.77, δ 166.35, δ 157.20, δ 148.05, 5139.83, δ 131.96, δ 129.16, δ 121.94, δ 120.03, δ 116.27, δ 114.07, δ 107.29, δ 100.86, δ 55.22.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₄ 271.09649 (monoisotopic mass), found 271.09631; [M+Na]⁺ calculated C₁₆H₁₄O₄Na 293.07843 (monoisotopic mass), found 293.07863.

2′-hydroxy-2,4′-dimethoxychalcone (13)

yellow solid (yield 46%); pf 74.7-77.9° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 12.87 (OH, 1H, s), δ 7.51 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.40 (H-6′, 1H, d, J=8.8 Hz), δ 7.21 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.16 (H-6, 1H, dd, J=7.6 Hz and J=0.8 Hz), δ 6.70 (H-4, 1H, td, J=1.2 Hz and J=8.0 Hz), δ 6.37 (H-3, 1H, d, J=8.4 Hz), δ 6.28 (H-5, 1H, d, J=7.6 Hz), δ 5.78 (H-5′, 1H, dd, J=2.4 Hz and J=9.2 Hz), δ 5.72 (H-3′, 1H, d, J=2.4 Hz), δ 3.22 (OCH₃, 3H, s), δ 3.14 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 192.44, δ 166.80, δ 166.42, δ 158.93, δ 139.26, δ 132.30, δ 131.99, δ 128.88, δ 123.48, δ 120.72, δ 120.59, δ 114.04, δ 111.56, δ 107.34, δ 100.85, δ 55.24, δ 54.64.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₄ 285.11214 (monoisotopic mass), found 285.11237; [M+Na]⁺ calculated C₁₇H₁₆O₄Na 307.09408 (monoisotopic mass), found 307.09351.

2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a)

yellow solid (64% yield); pf 138.6-139.0° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 12.24 (OH, 1H, s), δ 7.47 (H-6′, 1H, d, J=7.6 Hz), δ 7.16 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.12 (C_(α)H—CO, 1H, d, J=15.6 Hz) δ 7.06 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 6.76 (H-4′, 1H, t, J=8 Hz), δ 6.34 (H-3 and H-5, 2H, d, J=8.4 Hz), δ 6.21-6.17 (H-3′ and H-5′, 2H, m), δ 4.77 (H-1″, 1H, t, J=3.2 Hz), δ 3.05-2.99 (H_(α)-5″, 1H, m), δ 32.83-2.74 (H_(β)-5″, 1H, m), δ 1.16-0.78 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 194.04, δ 163.64, δ 159.70, δ 145.34, δ 136.34, δ 130.80, δ 130.35, δ 128.14, δ 120.05, δ 118.86, δ 118.17, δ 116.74, δ 107.43, δ 95.97, δ 61.63, δ 56.84, δ 29.97, δ 24.95, δ 18.51, δ 18.01.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₀H₂₁O₄ 325.14344 (monoisotopic mass), found 325.14319; [M+Na]⁺ calculated C₂₀H₂₀O₄Na 347.12538 (monoisotopic mass), found 347.12539.

2′,4-dihydroxychalcone (14)

yellow solid (60% yield); pf 148.8-150.2° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 12.15 (OH, 1H, s), δ 8.17 (OH, 1H, s), δ 7.31 (H-6′, 1H, d, J=7.2 Hz) δ 6.98 (C_(β)H, 1H, d, J=15.6 Hz), δ 6.93 (C_(α)H—CO, 1H, d, J=15.2 Hz), δ 6.85 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 6.60 (H-4′, 1H, t, J=7.2 Hz), δ 6.05-5.99 (H-3, H-3′, H-5 and H-5′, 4H, m). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 194.02, δ 163.62, δ 160.51, δ 145.79, δ 136.21, δ 131.28, δ 130.26, δ 126.50, δ 120.09, δ 118.81, δ 118.03, δ 117.10, δ 115.99.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₅H₁₃O₃ 241.08592 (monoisotopic mass), found 241.08620; [M+Na]⁺ calculated C₁₅H₁₂O₃Na 263.06787 (monoisotopic mass), found 263.06769.

2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a)

yellow solid (yield 38%); pf 83.7-89.3° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 6.88 (H-2 and H-6, 2H, d, J=8.4 Hz), δ 6.78-6.72 (C_(p)H, H-4′ and H-6′, 3H, m), δ 6.57 (C_(α)H—CO, 1H, d, J=16 Hz), δ 6.38 (H-3′, 1H, d, J=8 Hz), δ 6.32 (H-3 and H-5, 2H, d, J=8.8 Hz), δ 6.27 (H-5′, 1H, d, J=7.2 Hz), δ 4.75 (H-1″, 1H, t, J=3.2 Hz), δ 3.14 (OCH₃, 3H, s), δ 3.06-3.01 (H_(α)-5″, 1H, m), δ 2.83-2.78 (H_(p)-5″, 1H, m), δ 1.28-0.79 (H-2″, H3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 191.69, δ 159.05, δ 158.15, δ 142.08, δ 132.63, δ 129.91, δ 129.81, δ 129.75, δ 128.52, δ 125.24, δ 120.52, δ 116.72, δ 111.94, δ 96.01, δ 61.63, δ 55.28, δ 30.02, δ 24.98, δ 18.57.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₁H₂₃O₄ 339.15909 (monoisotopic mass), found 339.15784; [M+Na]⁺ calculated C₂₁H₂₂O₄Na 361.14103 (monoisotopic mass), found 361.14116.

4-hydroxy-2′-methoxychalcone (15)

yellow solid (82% yield); pf 135.3-138.0° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 8.05 (OH, 1H, s), δ 6.66 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 6.61-6.57 (C_(β)H, H-4′ and H-6′, 3H, m), δ 6.36 (C_(α)H—CO, 1H, d, J=16 Hz), δ 6.23 (H-3′, 1H, d, J=8 Hz), δ 6.12 (H-5′, 1H, t, J=7.6 Hz), δ 5.99 (H-3 and H-5, 2H, d, J=8.4 Hz), δ 2.99 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 191.81, δ 159.78, δ 158.07, δ 142.66, δ 132.48, δ 130.34, δ 129.88, δ 129.74, δ 126.77, δ 124.30, δ 120.49, δ 115.90, δ 111.92, δ 55.26.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₃ 255.10157 (monoisotopic mass), found 255.10180; [M+Na]⁺ calculated C₁₆H₁₄O₃Na 277.08352 (monoisotopic mass), found 277.08348.

2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a)

yellow solid (15% yield); pf 134.7-135.9° C. ¹H NMR (400 MHz, (CDCl₃): δ 7.73 (H-6′, 1H, d, J=8 Hz), δ 7.64 (C_(β)H, 1H, d, J=16 Hz), δ 7.53 (H-2 and H-6, 2H, d, J=8 Hz), δ 7.38 (C_(α)H—CO, 1H, d, J=16 Hz), δ 7.05 (H-3 and H-5, 2H, d, J=8.8 Hz), δ 6.56 (H-5′, 1H, dd, J=2.4 Hz, J=8 Hz), δ 6.49 (H-3′, 1H, d, J=2.4 Hz), δ 5.47 (H-1″, 1H, t, J=2.8 Hz), δ 3.90-3.87 (H_(α)-5″, OCH₃, 7H, m), δ 3.61 (H_(β)-5″, 1H, m), δ 2.03-1.59 (H-2″, H-3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 190.75, δ 163.98, δ 160.28, δ 158.71, 5142.14, δ 132.76, δ 129.87, δ 128.90, δ 125.26, δ 122.49, δ 116.65, δ 105.10, δ 98.70, δ 96.18, δ 62.07, δ 55.77, δ 55.55, δ 30.22, δ 25.13, δ 18.64.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₂₂H₂₅O₅ 369.16965 (monoisotopic mass), found 369.16998; [M+Na]⁺ calculated C₂₂H₂₄O₅Na 391.15159 (monoisotopic mass), found 391.15055.

4-hydroxy-2′,4′-dimethoxychalcone (16)

yellow solid (yield 92%); pf 139.9-142.2° C. ¹H NMR (400 MHz, (CDCl₃): δ 12.87 (OH, 1H, s), δ 7.51 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.40 (H-6′, 1H, d, J=8.8 Hz), δ 7.21 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.16 (H-6, 1H, dd, J=7.6 Hz, J=0.8 Hz), δ 6.70 (H-4, 1H, td, J=8.0 Hz, J=1.2 Hz), δ 6.37 (H-3, 1H, d, J=8.4 Hz), δ 6.28 (H-5, 1H, d, J=7.6 Hz), δ 5.78 (H-5′, 1H, dd, J=9.2 Hz, J=2.4 Hz), δ 5.72 (H-3′, 1H, d, J=2.4 Hz), δ 3.22 (OCH₃, 3H, s), δ 3.14 (OCH₃, 3H, s). ¹³C NMR (100 MHz, CDCl₃): δ 191.31, δ 164.13, δ 160.38, δ 158.10, δ 142.81, δ 132.80, δ 130.32, δ 127.89, δ 124.68, δ 122.29, δ 115.98, δ 105.14, δ 98.75, δ 55.77, δ 55.57.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₇H₁₇O₄ 285.11214 (monoisotopic mass), found 285.11192; [M+Na]⁺ calculated C₁₇H₁₆O₄Na 307.09408 (monoisotopic mass), found 307.09369.

4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a)

yellow solid (yield 66%); pf 134.7-135.9° C. ¹H NMR (400 MHz, (CDCl₃): δ 8.03 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 7.78 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.58 (H-2′ and H-6′, 2H, d, J=8.8 Hz), δ 7.43 (C_(α)H—CO, 1H, d, J=15.6 Hz), δ 7.08 (H-3 and H-5, 2H, d, J=8.4 Hz), δ 6.99 (H-3′ and H-5′, 2H, d, J=8.4 Hz), δ 5.48 (H-1″, 1H, t, J=2.8 Hz), δ 3.91-3.85 (H_(α)-5″, 1H, m), δ 3.89 (OCH₃, 3H, s), δ 3.65-3.60 (H_(β)-5″, 1H, m), δ 2.02-1.60 (H-2″, H-3″ and H-4″, 6H, m). ¹³C NMR (100 MHz, CDCl₃): δ 188.84, δ 163.29, δ 159.00, δ 143.88, δ 131.37, δ 130.73, δ 129.98 δ 128.53, δ 119.81, δ 116.72, δ 113.80, δ 96.17, δ 62.06, δ 55.50, δ 30.20, δ 25.13, δ 18.61.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺calculated C₂₁H₂₃O₄ 339.15909 (monoisotopic mass), found 339.15756; [M+Na]⁺ calculated C₂₁H₂₂O₄Na 361.14103 (monoisotopic mass), found 361.14116.

4-hydroxy-4′-methoxychalcone (17).

yellow solid (96% yield); pf 171.3-175.8° C. ¹H NMR (400 MHz, (CD₃)₂CO): δ 8.17 (H-2 and H-6, 2H, d, J=8.8 Hz), δ 7.77 (C_(β)H, 1H, d, J=15.6 Hz), δ 7.79-7.71 (H-2′ and H-6′, 2H, m), δ 7.73 (C_(α)H—CO, 1H, d, J=16 Hz), δ 7.10 (H-3′ and H-5′, 2H, d, J=8.8 Hz), δ 6.96 (H-3 and H-5, 2H, d, J=8.8 Hz), δ 3.94 (OCH₃, 3H, s). ¹³C NMR (100 MHz, (CD₃)₂CO): δ 187.24, δ 163.39, δ 159.86, δ 143.40, δ 131.43, δ 130.55, δ 130.51, δ 126.88, δ 118.71, δ 115.86, δ 113.75, δ 55.03.

HRMS (ESI− FT-ICR) m/z: [M+H]⁺ calculated C₁₆H₁₅O₃ 255.10157 (monoisotopic mass), found 255.10177; [M+Na]³⁰ calculated C₁₆F₁₄O₃Na 277.08352 (monoisotopic mass), found 277.08332.

Chromatographic Conditions for Determining the Purity

Analytical purification by means of HPLC was carried out with a Waters 2690 Separation Module, equipped with a 20-μl Rheodyne Model 8125 Injector and a Multi-Wavelength Programmable Model M486 Detector (PDA). Empower Chromatography Manager Software was used for data analysis. The purity, determined by HPLC, of the compounds subjected to biological tests was greater than 95%.

Compound A, Column: Phenomenex Luna C18, 5.0 μm (150×4.6 mm). Eluent A) aqueous solution of trifluoroacetic acid 0.03% (v/v). Eluent B) acetonitrile. Elution gradient: for 1 minute 80% A and 20% B; 1 to 10 minutes 60% A and 40% B; from 10 to 20 minutes 100% of B; 20 to 25 minutes 80% A and 20% B. Flow: 1.0 ml/min. Detector: UV lamp at wavelength 290 nm. Retention time (R_(t))=7.90 min.

Compound B, Column: Phenomenex Luna C18, 5.0 μm (250×4.6 mm). Eluent A) water/acetonitrile=95:5 (v/v). Eluent B) water/acetonitrile=5:95 (v/v). Elution gradient: for 5 minutes A:B=50:50; from 5 to 20 minutes up to 100% of B; from 20 to 25 minutes 100% of B. Flow: 1.0 ml/min. Detector: UV lamp at wavelength 295 nm. Retention time (R_(t))=13.12 min.

Compound E, Column: Phenomenex Luna C18, 5.0 μm (250×4.6 mm). Eluent A) methanol. Eluent B) water. Elution gradient: for 6 minutes A:B=65:35; from 6 to 8 minutes up to 81% of A; from 8 to 15 minutes A:B=81:19; from 15 to 20 minutes up to 65% of A. Flow: 1.0 ml/min. Detector: UV lamp at wavelength 325 nm. Retention time (R_(t))=5.02 min.

Compound F, Column: Phenomenex Luna C18, 5.0 μm (250×4.6 mm). Eluent: methanol/water (90:10, v/v). Flow: 1.0 ml/min. Detector: UV lamp at wavelength 237 nm. Retention time (R_(t))=5.83 min.

For compounds 1-17, HPLC analytical separations were performed using a Luna C18 stainless steel column, 5 μm (250×4.6 mm internal diameter, purchased from Phenomenex Inc.) Eluent A) water/acetonitrile (95:5, v/v). Eluent B) water/acetonitrile=5:95 (v/v). Elution gradient: for 5 minutes A:B=50:50; for 15 minutes up to 100% of B; for 5 minutes 100% of B. Flow: 1.0 ml/min. Detector: UV lamp at wavelength 200-400 nm.

Compound 1, 95.01% R_(t)=11.88 min (at 295 nm); compound 2, 98.41% R_(t)=15.67 min (at 295 nm); compound 3, 98.92 R_(t)=17.98 min (at 295 nm); compound 4, 99.29% R_(t)=14.76 min (at 295 nm); compound 5a, 98.28% R_(t)=19.44 min (at 295 nm); compound 5, 99.76% R_(t)=13.39 min (at 295 nm); compound 6a, 100% R_(t)=19.45 min (at 295 nm); compound 7a, 99.85% R_(t)=19.26 min (at 295 nm); compound 7, 99.36% R_(t)=12.98 min (at 295 nm); compound 8a, 99.98% R_(t)=20.95 min (at 295 nm); compound 8, 98.87% R_(t)=12.61 min (at 295 nm); compound 8b, 97.40% R_(t)=11.94 min (at 295 nm); compound 9, 100% R_(t)=18.30 min (at 295 nm); compound 10, 99.29% R_(t)=18.12 min (at 295 nm); compound 11a, 100.00% R_(t)=21.01 min (at 295 nm); compound 11, 96.25% R_(t)=13.15 min (at 295 nm); compound 12, 95.24% R_(t)=13.15 min (at 295 nm); compound 13, 99.41% R_(t)=18.78 min (at 295 nm); compound 14a, 98.68% R_(t)=21.01 min (at 295 nm); compound 14, 99.31% R_(t)=12.77 min (at 295 nm); compound 15a, 98.84% R_(t)=18.43 min (at 295 nm); compound 15, 95.57% R_(t)=8.67 min (at 295 nm); compound 16a, 100.00% R_(t)=17.83 min (at 295 nm); compound 16, 99.53% R_(t)=8.18 min (at 295 nm); compound 17a, 95.00% R_(t)=17.41 min (at 295 nm); compound 17, 98.40% R_(t)=8.93 min (at 295 nm).

Cell Lines and Treatments

The cell lines DND41 (ACC 525, DSMZ, Braunschweig, GERMANY), KOPTK1 (RRID: CVCL_4965) were maintained in culture in RPMI-1640 (Gibco, Carlsbad, Calif., USA) with 10% fetal bovine serum. TALL-1 cells (ACC-521: DSMZ, Braunschweig, GERMANY) were cultured in RPMI-1640 (Gibco, Carlsbad, Calif., USA) supplemented with 20% fetal bovine serum, while HaCaT cells (ACC-771: DSMZ, Braunschweig, GERMANY) were maintained in Eagle's culture medium according to Dulbecco (Gibco, Carlsbad, Calif., USA) containing 10% fetal bovine serum. Cells were treated with the naturally-occurring compounds A-H or with compounds 1-17 for times and concentrations indicated in the text.

Proliferation Analysis and Calculation of IG₅₀

Cells were seeded in 96-well plates with a density of 5×10⁵ cells/ml (5×10⁴ cells per well) and treated for the times and the concentrations of the various compounds, as indicated in the text.

All treatments were carried out in triplicate, including control treatments. All treatment reactions contained a final concentration of 1% DMSO (D5879; Sigma-Aldrich, St Louis, Mo., USA). To quantify vitality, cells were assayed by the MTS CellTiter 96® AQueous One Solution Cell Proliferation Assay (G3580; Promega, Madison, Wis., USA). Absorbance was detected at 490 nm using the GloMax Multidetection System instrument (Promega, Madison, Wis., USA). Data were collected in the form of absorbance units (ABSs) and standardized to obtain the proliferation rate (MTS) through the equation:

% cell proliferation=(ABS_(cell culture+compound)−ABS_(culture medium+compound)/(ABS_(cell culture+DMSO)−ABS_(culture medium+DMSO))×100

The 50% inhibition concentration was calculated using the GraphPad Prism software program (GraphPad Software Inc., La Jolla, Calif., USA).

Protein Extraction, Immunoblotting, Antibodies

Laemmli Sample Buffer (161-0737; Bio-Rad Laboratories Inc., Hercules, Calif., USA) was added to each cell pellet. Cells were lysed by ultrasonic sonication and to each mixture 5% 2-mercaptoethanol (161-0710; Bio-Rad Laboratories Inc., Hercules, Calif., USA) was added. Samples were denatured at 100° C. for 5 min and protein mixtures were separated by means of Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis using 8% acrylamide and transferred onto nitrocellulose membranes. After transfer, the membranes pre-saturated in 5% Blot Dry Fat Milk (1706404; Bio-Rad Laboratories Inc., Hercules, Calif., USA) were incubated for 16 hours at +4° C. with the following primary antibodies diluted at 1:1000 in 5% Dry Fat Milk (1706404; Bio-Rad Laboratories Inc., Hercules, Calif., USA): Notch1Val1744 (2421; Cell Signaling Technology, Beverly, Mass., USA), Notch3 (2889; Cell Signaling Technology, Beverly, Mass., USA) and β-actin (sc-47778; Santa Cruz Biotechnology, Santa Cruz, Calif., USA). Subsequently, filters were incubated for 1 hour at room temperature with the following secondary antibodies: anti-rabbit (sc-2004, Santa Cruz Biotechnology, Santa Cruz, Calif., USA) or anti-mouse (sc-2005, Santa Cruz Biotechnology, Santa Cruz, Calif., USA). Chemiluminescence signal detection was performed using the ECL Advanced Detection System substrate (RPN2135; E Healthcare UK Limited, Buckinghamshire, UK).

Total RNA Isolation and Real-Time PCR

Total RNA from the cell pellets was extracted using TRIzol reagent (Ser. No. 15/596,018, Invitrogen, Carlsbad, Calif., USA) following the manufacturer's instructions. From 100 ng to 2 μg of total RNA per sample was retroscribed using the High Capacity cDNA Reverse Transcription Kit (4368814; Applied Biosystems, Foster City, Calif., USA) and following the manufacturer's instructions. Real-time PCR experiments were performed using ViiA™ 7 Real-Time PCR System (Applied Biosystems, Foster City, Calif., USA). Taqman Gene Expression Master Mix and Taqman Gene Expression Assays for HES1 (Hs00172878_m1), cMYC (Hs00905030_m1), DELTEX1 (Hs01092201_m1) and GAPDH (Hs02758991_g1) were provided by Applied Biosystems, Foster City, Calif., USA. The results were analyzed using the ΔΔCt method, normalizing the obtained values with respect to those obtained for GAPDH.

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1.-10. (canceled)
 11. An inhibitor of Notch signaling of formula (I)

wherein X and Y are carbon atoms bound by a single or double bond having, independently, an E or Z configuration; R_(1′) is hydrogen, halogen, OR_(A), C(═O)R_(A), C(═O)OR_(A), OC(═O)R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), N(R_(A))₂, NHC(═O)R_(A), C(═O)N(R_(A))₂, or C(R_(A))₃; R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OR_(B); C(═O)R_(B); C(═O)OR_(B); OC(═O)R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B))₂; NHC(═O)R_(B); C(═O)N(R_(B))₂; C(R_(B))₃; a linear or branched, saturated or unsaturated C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl; a C₅₋₇ heterocyclic group; wherein at each occurrence R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group; and pharmaceutically acceptable salts thereof, with the exception of compounds of formula (I) wherein R_(1′), R_(2′), R_(3′), R₁, R₂, R₃ have the meanings indicated in the following table and X and Y are carbon atoms bound by a double bond: No. R1′ R2′ R3′ R1 R2 R3 101 H H H H H H 102 H H H OH H H 103 H H H H OH H 104 H H H H H OH 105 OH H H H H H 106 OH H H OH H H 107 OH H H H OH H 108 OH H H H H OH 109 OH H H H H OCH₃ 110 OH H H H OCH₃ OCH₃ 111 OH H H H H CH₃ 112 OH OCH₃ OCH₃ H H Br 113 OCH₃ H OCH₃ H H Cl 114 OCH₃ H OCH₃ H H Br 115 H OCH₃ OCH₃ H H Cl 116 H OCH₃ OCH₃ H H SCH₃ 117 OCH₃ H H H H F 118 H H OCH₃ OCH₃ H H 119 H H OCH₃ H H Cl 120 H H CH₃ H H N(CH₃)₂ 121 H H CH₃ H H F 122 H H CH₃ H H Cl 123 H H CH₃ H H SCH₃ 124 NH₂ H H H H H 125 NH₂ H H H H Cl 126 NH₂ H H H H OCH₃ 127 H H NH₂ H H H 128 H H NH₂ Cl H H 129 H H NH₂ H H Cl 130 H H NH₂ Cl H Cl 131 OH H OCH₃ H OCH₃ OCH₃ 132 OCH₃ H OCH₃ H H OCH₃ 133 OH H OCH₃ H OH OCH₃ 134 OH H OCH₃ H H OH 135 OH H OCH₃ H OCH₃ H 136 OH H H H H OH 137 OCH₃ OCH₃ OCH₃ H OH OCH₃ 138 OCH₃ OCH₃ OCH₃ H H OCH₃ 139 OCH₃ OCH₃ OCH₃ H F OCH₃ 140 H H CH₃ H OH OCH₃ 141 OCH₃ OCH₃ OCH₃ H OH OH 142 H OCH₃ OCH₃ H OCH₃ OCH₃ 143 OCH₃ H OCH₃ H H OCH₃ 144 H H F H H F 145 OH H OCH₃ H H Cl 146 H H OCH₃ H H OCH₃ 147 H OCH₃ OCH₃ H H OCH₃ 148 H H CH₃ H H CH₃ 149 H H OCH₃ H H OCH₃ 150 OH H OCH₃ H OCH₃ OCH₃ 151 H H CH₃ H H OCH₃ 152 OH H OH H H H 153 OH H H H OH H 154 OH H H Cl H H 155 OH H H H H H 156 OH H H H H Cl 157 OH H H H H Br 158 OH H H H H OCH₃ 159 OH H OH H H OH 160 OCH₃ H OCH₃ H F H 161 OCH₃ H OCH₃ Cl H H 162 OCH₃ H OCH₃ OCH₃ H OCH₃ 163 OH H OCH₃ Cl H H 164 OH H OCH₃ H H Cl 165 OH H OCH₃ Cl H H 166 OH H OCH₃ H F H 167 OH H OCH₃ H OCH₃ H 168 OH H OCH₃ OCH₃ OCH₃ H 169 OH H OCH₃ H OCH₃ OCH₃ 170 OH H OCH₃ OCH₃ H OCH₃ 171 OH H OCH₃ OCH₃ OCH₃ OCH₃ 172 H H H H H H 173 OH H H H H H 174 H OH H H H H 175 H H OH H H H 176 H H H OH H H 177 H H H H OH H 178 H H H H H OH 179 H H OH OH H H 180 H H OH H OH H 181 H H OH H H OH 182 H H H OH H OH 183 OH H H OH H OH 184 H OH H OH H OH 185 H H OH OH H OH 186 H OH OH OH H OH 187 H H H OH CH₂CH═CH₂ OH 188 H H OCH₃CO H H H 189 H H OCH₃ H H H 190 H H H OCH₃CO H H 191 H H H OCH₃ H H 192 H H OCH₃ OH H H 193 H H H OH H OCH₃CO 194 H H OH OH H OH 195 H H H H H H 196 H H Cl H H Cl 197 H H CH₃ H H CH₃ 198 H Cl H CH₃ H CH₃ 199 H H H CH₃ H CH₃ 200 H H CH(CH₃)₂ H H CH₃ 201 Cl H Cl H H CH₃ 202 H H Cl H H CH₃ 203 H H CH₃ H H Cl 204 OH H OH H H OH 205 OH OCH₃ OH H OH OH 206 OH OH OH H OH OH 207 OH OCH₃ OH H OH OCH₃


12. The inhibitor of Notch signaling of formula (I) according to claim 11, wherein X and Y are carbon atoms bound by a double bond having, independently, an E or Z configuration.
 13. The inhibitor of Notch signaling of formula (I) according to claim 11, wherein R_(1′) is hydrogen, halogen, OR_(A), OC(═O)R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), C(R_(A))₃; R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen; halogen; OR_(B); C(═O)R_(B); C(═O)OR_(B); OC(═O)R_(B); SR_(B); SO₂R_(B); SO₃R_(B); OSO₂R_(B); OSO₃R_(B); N(R_(B))₂; NHC(═O)R_(B); C(═O)N(R_(B))₂; C(R_(B))₃; at each occurrence, R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen and sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group;
 14. The inhibitor of Notch signaling of formula (I) according to claim 11, wherein R_(1′) is hydrogen, halogen, OR_(A), OC(═O)R_(A), SR_(A), SO₂R_(A), SO₃R_(A), OSO₂R_(A), OSO₃R_(A), C(R_(A))₃; R_(2′), R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: a linear or branched, saturated or unsaturated C₁₋₇ acyclic aliphatic group optionally containing up to three heteroatoms independently selected from nitrogen, oxygen or sulfur; a C₅₋₇ cycloalkyl group; a phenyl group; a C₅₋₇ heterocyclic group; and R_(A) has the meaning indicated in claim
 11. 15. The inhibitor of Notch signaling of formula (I) according to claim 11, wherein X and Y are carbon atoms bound by a double bond having, independently, an E or Z configuration; R_(1′) is OR_(A); R_(2′) is hydrogen; R_(3′), R₁, R₂, R₃ are the same or different and independently selected from: hydrogen and OR_(B); R₃ is OR_(B); and at each occurrence R_(A) and R_(B) are independently selected from: hydrogen; a linear or branched, saturated or unsaturated C₁₋₇ aliphatic group, preferably a linear or branched, saturated or unsaturated C₁₋₃ aliphatic group; a C₅₋₇ heterocyclic group.
 16. The inhibitor of Notch signaling of formula (I) according to claim 11 selected from: 2′-hydroxy-4,4′-dimethoxychalcone (3) 2′-hydroxy-4,4′-dimethoxy-3-(tetrahydropyran-2-yloxy)chalcone (5a) 2′,3-dihydroxy-4,4′-dimethoxychalcone (5) 2′-hydroxy-3,4-dimethoxy-4′-(tetrahydropyran-2-yloxy)chalcone (6a) 2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (7a) 2′,4-dihydroxy-3,4′-dimethoxychalcone (7) 2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a) 2′,4-dihydroxy-4′-methoxychalcone (8) 2′,4-dihydroxy-4′-methoxydihydrochalcone (8b) 2′-hydroxy-4′-methoxychalcone (9) 2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a) 2′,3-dihydroxy-4′-methoxychalcone (11) 2,2′-dihydroxy-4′-methoxychalcone (12) 2′-hydroxy-2,4′-dimethoxychalcone (13) 2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a) 2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a) 4-hydroxy-2′-methoxychalcone (15) 2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a) 4-hydroxy-2′,4′-dimethoxychalcone (16) 4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a) 4-hydroxy-4′-methoxychalcone (17).
 17. The inhibitor of Notch signaling of formula (I) according to claim 11 selected from: 2′-hydroxy-4,4′-dimethoxychalcone (3) 2′,3-dihydroxy-4,4′-dimethoxychalcone (5) 2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (7a) 2′,4-dihydroxy-3,4′-dimethoxychalcone (7) 2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a) 2′,4-dihydroxy-4′-methoxychalcone (8) 2′-hydroxy-4′-methoxychalcone (9) 2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a) 2′,3-dihydroxy-4′-methoxychalcone (11) 2,2′-dihydroxy-4′-methoxychalcone (12) 2′-hydroxy-2,4′-dimethoxychalcone (13) 2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a) 2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a) 4-hydroxy-2′-methoxychalcone (15) 2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a) 4-hydroxy-2′,4′-dimethoxychalcone (16) 4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a) 4-hydroxy-4′-methoxychalcone (17).
 18. Pharmaceutical composition comprising at least one inhibitor of Notch signaling of formula (I) according to claim 11 and at least one pharmaceutically acceptable vehicle or excipient.
 19. An inhibitor of Notch signaling selected from: 2′-hydroxy-4,4′-dimethoxychalcone (3) 2′-hydroxy-4,4′-dimethoxy-3-(tetrahydropyran-2-yloxy)chalcone (5a) 2′,3-dihydroxy-4,4′-dimethoxychalcone (5) 2′-hydroxy-3,4-dimethoxy-4′-(tetrahydropyran-2-yloxy)chalcone (6a) 2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (7a) 2′,4-dihydroxy-3,4′-dimethoxychalcone (7) 2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a) 2′,4-dihydroxy-4′-methoxychalcone (8) 2′,4-dihydroxy-4′-methoxydihydrochalcone (8b) 2′-hydroxy-4′-methoxychalcone (9) 2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a) 2′,3-dihydroxy-4′-methoxychalcone (11) 2,2′-dihydroxy-4′-methoxychalcone (12) 2′-hydroxy-2,4′-dimethoxychalcone (13) 2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a) 2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a) 4-hydroxy-2′-methoxychalcone (15) 2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a) 4-hydroxy-2′,4′-dimethoxychalcone (16) 4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a) 4-hydroxy-4′-methoxychalcone (17).
 20. The inhibitor of Notch signaling according to claim 19 selected from: 2′-hydroxy-4,4′-dimethoxychalcone (3) 2′,3-dihydroxy-4,4′-dimethoxychalcone (5) 2′-hydroxy-3,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (7a) 2′,4-dihydroxy-3,4′-dimethoxychalcone (7) 2′-hydroxy-4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (8a) 2′,4-dihydroxy-4′-methoxychalcone (8) 2′-hydroxy-4′-methoxychalcone (9) 2′-hydroxy-4′-methoxy-3-(tetrahydropyran-2-yloxy)chalcone (11a) 2′,3-dihydroxy-4′-methoxychalcone (11) 2,2′-dihydroxy-4′-methoxychalcone (12) 2′-hydroxy-2,4′-dimethoxychalcone (13) 2′-hydroxy-4-(tetrahydropyran-2-yloxy)chalcone (14a) 2′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (15a) 4-hydroxy-2′-methoxychalcone (15) 2′,4′-dimethoxy-4-(tetrahydropyran-2-yloxy)chalcone (16a) 4-hydroxy-2′,4′-dimethoxychalcone (16) 4′-methoxy-4-(tetrahydropyran-2-yloxy)chalcone (17a) 4-hydroxy-4′-methoxychalcone (17). 